The size of the effect is astounding. Cross-class friendships are a better predictor of upward mobility than school quality, job availability, community cohesion or family structure. If these results are true, then we have largely ignored a powerful way to help people realise the American dream.
When you have a densely connected network like that, not only are the friendships more rewarding, but everyone else also becomes more important to each other for mutual support, like Metcalfe’s Law. A densely layered quilt is much stronger than a seam sewn by a single string.
The club model teaches us something: organizations that endure don’t try to include everyone. They’re clear about their identity, even as that identity evolves. Some clubs that were men-only for centuries now welcome women. They haven’t survived by being vague, they’ve survived by being clear, then changing what that clarity meant over time.